The chmod command sets Linux file permissions using three octal digits — one each for owner, group and others. Each digit (0–7) is the sum of read (4), write (2) and execute (1). This chart explains the digits and the most common permission modes.
Octal digit meaning
| Digit | Symbols | Permission |
|---|---|---|
| 0 | --- | No permission |
| 1 | --x | Execute |
| 2 | -w- | Write |
| 3 | -wx | Write + execute |
| 4 | r-- | Read |
| 5 | r-x | Read + execute |
| 6 | rw- | Read + write |
| 7 | rwx | Read + write + execute |
Common chmod modes
| chmod | Symbolic | Meaning |
|---|---|---|
| 644 | rw-r--r-- | Files: owner edits, others read |
| 755 | rwxr-xr-x | Folders / scripts: owner full, others read+run |
| 600 | rw------- | Private file (owner only) |
| 700 | rwx------ | Private folder (owner only) |
| 666 | rw-rw-rw- | Everyone read + write |
| 777 | rwxrwxrwx | Everyone full (avoid) |